JOURNAL of the Tunisian Chemical Society

Sol-gel processing of ZrO₂ is performed via hydrolytic polycondensation of zirconium tetrapropoxide Zr(OPr)₄ in the presence of acetic acid. The gelation times as well as the aspects of the produced gels are studied as functions of the molecular ratios h = H₂O/ Zr(OPr)₄ and k = CH₃COOH/ Zr(OPr)₄. I.R. study shows that molecular precursors of general formula Zr(OPr)_x (AC)_y are formed in which the bidentate acetates (Ac) replace the OPr groups and are directly bounded to zirconium by both chelation and bridging. Ac ligands exhibit a strong resistance to the action of water and their departure by heating is only possible at temperatures higher than 200°C. Water, indispensable for hydrolysis of Zr(OPr)_x (Ac) species, is formed in-situ by action of acetic acid on n-PrOH. Further addition of water isn't necessary.

C. Ben Amara, N. Gharbi, H. Zarrouk

Pages 27-34